<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        #parent{
            width: 100px;
            height: 100px;
            background: salmon;
        }
        .none{
            display: none;
        }
        .show{
            display: block;
        }
        </style>
</head>
<body>
    <div id="parent" class="none">

    </div>
    <button id="toggle">toggle</button>
    <script>
    var toggle = document.getElementById("toggle");
    var parent = document.getElementById("parent");
    toggle.onclick =()=>{
        // if(parent.className =="none"){
        //     parent.className = "show"
        // }else{
        //     parent.className ="none"
        // }
        parent.classList.toggle("none")
    }
    </script>
</body>
</html>